Video game console ROM emulator file
SMD is a file extension for a read-only memory (ROM) file extracted from a Sega Mega Drive cartridge. SMD stands for Sega Mega Drive. SMD files contain a copy of a Mega Drive game, which can be used with a Mega Drive emulator. SMD files allow the play of Mega Drive games on other operating systems, including Windows. SMD files are created with a flash cart and software proprietary to the flash cart used.
Learn more about .SMD files:
Visit the Sega web page.
Read more about Emulators at ITKnowledgeExchange.com.